hot corners

I've gotten so used to GNOME Shell's upper-left hot corner for bringing up the Overview that I find myself moving the cursor up there in Ubuntu 12.04's Unity. I used the ubuntu-tweak configuration tool to create hot corners in Unity. I downloaded it from the Ubuntu Tweak website, but you can get it by adding the PPA (https://launchpad.net/~tualatrix/+archive/ppa).

I ran ubuntu-tweak, navigated to Tweaks tab > Workspace, and set it up like this:

When I move the cursor to the upper-left hot corner to show the workspaces:

When I move the cursor to the lower-left hot corner to show running windows in the current workspace (workspace #2):